Nokia has hit data rates of up to 4.7Gbps in a trial, by aggregating eight 100 MHz channels in millimeter wave bands with 40 MHz of LTE spectrum. The key to very high speeds clearly lies in spectrum where applications can use at least 100 MHz of unencumbered airwaves, which means the bands above 20 GHz in most cases. However, these have challenges when it comes to range and penetration, and even 100 MHz channels are inadequate for some of the high capacity services envisaged for 5G. In the decade before we reach the even loftier heights of ‘6G’ and ‘terahertz spectrum’ (see separate item), the main solution will lie in aggregating ever larger numbers of channels, from ever-more disparate…